Oil or gas burner comprising a device for controlling the air supply in the blowing aperture of said burner



May 2, 1961 W AIJ OIL OR GAS BURNER COMPRISING A DEVICE FOR CONTROLLINGTHE AIR SUPPLY IN THE BLOWING APERTURE OF SAID BURNER Filed Sept. 18,1958 I III!IIIIIIIIIIIIIIIIIIIII INVENTOR. [0/555 DE/Y/JE/Z UnitedStates Patent FOR CONTROLLING THE AIR SUPPLY IN THE BLQWING APERTURE FSAID BURNER Wiebe Draijer, 161 Harstenhoekweg, Scheveningen, NetherlandsFiled Sept. 18, 1958, Ser. No. 761,770

Claims priority, application Netherlands Sept. 24, 1957 3 Claims. (Cl.158-115) The present invention relates to afuel burner (oil or gas),provided with a device for controlling the air supply in the blowingaperture of said burner, said blowing aperture being concentricallymounted around the burner.

The control of the amount of combustion air must be proportional to theamount of fuel. This can be obtained in several ways, however, nearlyall ways make use of 'controlling members (valves, scoops and the like)which are positioned atsome distance in front of the actual blowingaperture or jet. By this fact the velocity and the turbulence decreaseproportionately in the actual blowing aperture or jet, also calledthroat, when the amount of air is decreased.

In order to obtain a well shaped flame and an efficient combustion oneof the principal requirements is a close mixing of the air and theatomised fuel and this requirement is closely related to the velocity,the direction and the turbulence of the air. It is possible to keep thevelocity in the throat equal when using different amounts of air byadjusting the section of the throat (flexible throat). This, however, isnot suflicient and cannot be easily carried out, because of theturbulence and also the direction of the air supplied at a low loadnevertheless show considerable deviation at full load, which isexpressed in a less stable and less efficient flame.

The object of the present invention is to provide a device with whichthe velocity, the turbulence as well as the direction of the flow of aircan be adapted to the requirements which can be made in one burner fordifferent amounts of air and oil or gas.

In the device according to the invention therefore, means are providedat the exit of the air blowing aperture, which can be moved with regardto each other and which are provided with such apertures that at fullload the average air flow is moving therethrough substantially in anaxial direction and thatwhen the means move more towards each other thediameter of the throat decreases and also an air flow progressively isobtained which is more radially directed inwardly.

A detailed description of my invention will now be given in conjunctionwith theappended drawings in which: 4 Figure 1 is a longitudinalcross-section through an oil burner on the air controlling devicecomprising my invention.

Figure 2 is a cross-section of a hollow coaxial ring.

In the drawing an embodiment of the device according' to the inventionis described by way of examples for an oil burner. The" solid portion ofthe air controlling device shows the position for the lowest air supply,the dotted portion of the air controlling device shows the position forthe largest air supply.

The burner body is indicated with 1. The dotted line 2 indicates thecircumference of the cone of the fuel at lowest load. The dotted line 3indicates the circumference of said cone at the largest load.

A sleeve 4 surrounds the burner body 1. At the end Patented May 2, 1961of the sleeve 4 adjacent to the burner jet 5 a number of spoke-shapedmembers 6 are mounted. Said members 6 support a set of coaxial rings 7which form the mantle of a truncated cone. The top of said cone lies onthe axis of the burner body 1.

A second sleeve 8 is mounted concentrically around said sleeve 4 and isadapted to slide lengthwise. The sliding movement of said sleeve can becarried out by means of suitable members which are indicated at 10.

A number of spoke-shaped members 9 which also extend with an inclinationare mounted on the end of the slidable sleeve 8 adjacent to the jet 5.Said members 9 support some coaxial rings 11 which constitute with eachother a second truncated cone. The top of said second cone is alsosituated on the axis of the burner body. The top angles of said twoconical surfaces, however, differ over such an amount that when saidrings slide the outmost rings of both sets of rings will completelyclose first (side upper part of drawing), and afterwards the moreinwardly positioned rings etc. The air can be fed to the throat havingpressurized air control through an air box or also immediately from theatmosphere. Cooling of the sets of ring-shaped members 7, 11 takes placeby means of the air flowing alongside, however, both sets can be carriedout by means of ring-shaped tubes through which water or another coolantflows such as hollow tube 7a. One of said sets of ring-shapedmembers-also can be carried out as tubes. The embodiment last mentionedis preferred for use in very hot heavily loaded burners.

In most cases it will be suflicient to cool the hollow ring-shaped tubeslying nearest to the flame which in the present case is the fixed cone.In its open position the control member exclusively is a turbulencegenerator.

The average direction of the air flow is axial. The turbulencesare verysteady by the application of torusshaped rings and are beneficial for aclose mixing of the air andthe fuel mist.

In the partly closed position the passage is decreased from the outsideso that a decreased amount of air flows through a relatively narrowersection and secondly a radially and inwardly directed flow is generated.The turbulence therefore remains very good and the direction of the airis adjusted to the smaller flame.

In the completely closed position said change is made in the samedirection. However, an aperture around the burner remains free throughwhich a strongly decreased amount of air can flow which is stronglyradially directed. Said amount of air corresponds to the lowest load ofthe oil burner. In dependence from the embodiment said lowest loadshould be approximately 5 to /3 of the full load.

What is claimed is:

1. An oil or gas burner comprising, in combination, a fuel nozzle, meansfor controlling and directing combustion air positioned concentricallyaround said nozzle, said means comprising a fixed cone-shaped member anda second cone-shaped member in substantial nested relation; meansmounting said second cone-shaped member for movement toward and awayfrom the fixed member, each of said two members comprising a number ofconcentric toroidal rings forming ring-shaped openings between saidrings and arranged so that on moving the movable member away from thefixed member the effective flow area through the openings increases andthe general direction of the outflowing air continuously changes at thesame time from substantially ina radially inward direction to asubstantially axial direction, thereby providing proper conditions ofturbulence, direction and flow area for the combustion air stream withrespect to the fuel nozzle and rate of fuel supply.

2. The device of claim 1 in which the inner cone- 3 4 shapeq memberforms a greater angle with respectlto References Cited in the file ofthis patent the am the bumcf- UNITED STATES PATENTS 3. The device ofclaim 2 in which the torus-shaped rings which are nearest 'to the fuelcone, are tubes through which a coolant can be fed.

1,177,028 Fischer Mar. 28, 1916 5 2,690,213 Collinson Sept. 28, 1954

